look what happens:*I use the router WRT54GL and I port forward the ports I want to test and everything(TCP/UDP) goes clear.

*When I test the forwarded ports in my grandma's router (WRT120N) the UDP ports fail the test(the TCP Port works). It just works in the first time. When I click begin again it allways go UDP Failed even it's opened.

So you used the same system. Tested with the WRT54GL and they both pass. On the same system you tested the wrt120n and only TCP passed.

Good testing

By doing that you have confirmed it is not your system. The problem is in the wrt120n. So we may need to check some of the settings in it. We should also check for a firmware update, perhaps it is a bug and it has been fixed.

Shane

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If it was a problem with your system or my program then it would be failing on both routers

I have a linksys that I will be replacing. The port forwarding on it is totally screwed. When I use the port range forwarding page the rules only work once after I reboot the router and then fail every time after. But if I use the single port forwarding page or DMZ it passes every time.

Sounds like you have the same bug as me!

This is why I like Netgear lol

Shane

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oohsomething like that!in wrt120n:look.. I port forward the TCP/UDP port. I click to test and both are opened (great) . Click again (opened) (GREAT)I disable the port forward (TCP goes down) (ok) and UDP continues saying (Successful)

it's crazy!

hah

what do you think?

thanks!

*this is what is happening after I update today to the latest firmware!

It's true for UDP. It's UDP: it's packet-based. Unlike TCP where you have a "handshake" before you have a working connection, UDP is best-effort packet delivery.

Thus, a UDP test sends something to that port and checks if something comes back.

If an ICMP error comes back you know for sure that the port is closed. However, too many firewalls are set too tight and filter this ICMP message, or it doesn't go through the router correctly, or, or, or is filtered somewhere...

If a data packet comes back then you know that it's open. Of course, to get something back you must have something to the port which caused the application listening on that port to respond. Now most of the time, applications won't answer to packets which they don't understand. Of course, a UDP test cannot know which application runs on that port, i.e. what it has to send to get something back.

That means most of the time a UDP test won't get anything back and most of the time the test thus has to guess whether it means the port is open or not. And unfortunately, most tests won't correctly tell you the result "I don't know" but tell you either "open" or "closed" depending on the test developer's preference because who would use a test which tells you most of the time "I don't know"??

is that what u said? "UDP is a connectionless protocol. That means there is no way to tell a connection state of a UDP port. Thats why he says that. "